Asthma, a chronic illness affecting all ages, is increasing in prevalence. In the USA, ~ 18.9 million adults and 7.1 million children currently have asthma ? 1/12 the population. Asthma, which significantly affects the quality of life with no available cure, is managed mainly by symptomatic treatments with corticosteroids and ?2- agonists which, while effective, exert significant adverse effects. Improved, targeted therapies are needed for this allergic disease. Genetic and environmental factors, e.g, allergens and respiratory infections, trigger and exacerbate asthma. Immune responses differentiate CD4+ T cells into effector T cells that secrete inflammatory cytokines. In particular, asthma is characterized by increases in TH2 and TH17 effector cells that mediate influx of eosinophils and neutrophils, which produce the airway inflammation-related symptoms of asthma. Thus, suppression of pro-inflammatory cytokines and chemokines is an attractive therapeutic approach to dampen allergic responses in asthma. Protein ubiquitylation is a key regulatory mechanism of innate and adaptive immune systems mediating inflammation. Nedd4-family E3 ligases, including Itch, negatively regulate inflammatory immune responses by suppressing TH2 and TH17 differentiation and cytokine production. Genetic disruption of Itch leads to the development of multi-system immune disorders and lung inflammation. Itch exists in an auto-inhibited state with no ligase function; activation is achieved by binding of proteins such as Ndfip1, which restores its E3 ligase activity. Ndfip1 mice develop asthma-like lung inflammation linked to TH2 and -/- TH17 T-cells, and Ndfip protein activates Nedd4-family E3 ligases in cells, attenuating TH2 and TH17 cell functions. Finally, SNPs in Ndfip1 are linked to asthma and atopic dermatitis. Thus, Ndfip is a master suppressor of T-cell mediated inflammatory responses. The therapeutic hypothesis of the successful Phase I project was that that small molecule mimics of Ndfip1 can be used to selectively activate ubiquitylation cascades to limit TH2 and TH17 cytokine production and to dampen allergic inflammation. In the Phase I project a novel TR-FRET based homogeneous E3 assay was used to identify, in high throughput screening, small molecule mimics of Ndfip1 that selectively activated Itch in vitro and in cells. Selected activators induced Treg differentiation of CD4+ T-cells, and treatment of Ndfip1-/- cells with the Itch activator P0057892 suppressed production of the pro-inflammatory cytokine IL-4. In Phase II, lead optimization and additional preclinical studies (ADME/PK, efficacy in animal models) will be performed with selected agonists to ascertain their ability to modulate Itch functions and to dampen inflammation in relevant mouse models.